The belt drive should, with as little energy loss, and a minimum of servicing through retensioning as possible, transfer a relatively high amount of torque to an ever increasing number of auxilliary components. A longer
life and a lower breakdown danger is reached with open-flank fan belts and flat ribbed belts. In addition, smaller enlacement radii and thus, greater transmission ratios are possible, also - if the pre-tension is not too
high - the prevention of belt-slipping.
In contrast to the timing-belt, the energy of the belt drive is utilised by pressure force, and not by it's shape (gear-teeth). Originally a fan belt was used to drive the generator and
the cooling. If more torque was to be transferred, and the belt threatened to slip, several fan belts, and their respective pulley-wheels, were mounted parallel, e.g., in the air cooling of trucks.
In the meantime, the
motor car generators have become stronger and servo-pumps or air-conditioning compressors have been added. If the fan belt is not sufficiently tensioned, it has a tendency, particularly in the final stages of the
power steering, to slip, thus causing a very loud screeching noises. If the fan belt is too tight, the front bearings of the auxilliary components are overburdened.
Thus, the time has arrived for the flat- or the wedge-
shaped ribbed-belt. In addition, it drives, with its rear-side, (picture 3) the closely packed components. One disadvantage, in particular in transverse mounted engines: It is a little broader and increases the
construction length slightly. An additional advantage is, the energy loss when tranferring torque is lower.
Even though the service-minimising has made vast progress, the belt drive - if it has not been coupled with
a complicated vibration prevention - has not yet been able to benefit. whereby, the generator, and other components, even the waterpump, can be adjusted. Through the presence
of a built-in spring, the screws can be re-tightened directly after loosening them.
If the servicing has been sloppily done, the ability to transfer torque sinks when the generator is more
heavily burdened. The belt slips more and more and one runs the risk of breaking down somewhere with a discharged battery.